biology

RAB11B

RAB11B is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand RAB11B rather than just read about it. In short: Ras-related protein Rab-11B is a protein that in humans is encoded by the RAB11B gene. Rab11b is reported as most abundantly expressed in brain, heart and testes.

Key takeaways

RAB11B belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect RAB11B to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of RAB11B from memory before moving on to harder problems.

Reference excerpt

Ras-related protein Rab-11B is a protein that in humans is encoded by the RAB11B gene. Rab11b is reported as most abundantly expressed in brain, heart and testes. Rab (Ras-related in brain) proteins form the largest section of the Ras superfamily of small GTPases. The Rab family proteins regulate intracellular membrane trafficking processes including vesicle budding, tethering, and fusion. The isoforms Rab11a, Rab11b, and Rab11c/Rab25 constitute the Rab11 subfamily based on specific sequence motifs. While RAB11A is located on chromosome 15 and RAB11C on chromosome 1, RAB11B is placed on chromosome 19. Rab11 proteins are implicated in endocytosis and exocytosis. Rab11b is reported as most abundantly expressed in brain, heart and testes. Early studies with deletions of RAB11 homologs in Saccharomyces cerevisiae proved their importance in cell survival. Despite sharing high sequence homology, Rab11a and Rab11b appear to reside within distinct vesicle compartments. Majority of Rab11b neither colocalize with transferrin receptor nor with the polymeric IgA receptor. This protein also exhibits a dependence on the microtubule cytoskeleton that is different from Rab11a. High sequence diversity in the C-terminal hypervariable region is responsible for variable membrane targeting between these proteins.

Function Members of the Rab11 subfamily act in recycling of proteins from the endosomes to the plasma membrane, in transport of molecules from the trans-Golgi network to the plasma membrane and in phagocytosis. This subfamily also acts in polarized transport in epithelial cells. Whereas most studies refer to the Rab11a isoform, little is known about Rab11b so far. Rab11b localizes predominantly in the pericentriolar recycling compartment and serves as an important component of the vesicular machinery. It is required for the transfer of internalized transferrin from the recycling compartment to the plasma membrane for which active Rab11b as well as GTP hydrolysis is necessary.

Structure All Ras GTPases consist of a similar core structure and highly conserved P-loop, switch 1 and switch 2 regions. The Rab11b monomer exhibits a typical Ras-like, small GTPase fold with a six stranded β-sheet core (β1-β6) surrounded by five major α-helices (α1-α5) and one minor α-helix (α6). According to the sequence similarity to other Rab GTPases can be assumed that they show closely resembling characteristics in nucleotide binding and hydrolysis. However, Rab11 isoforms could differ in hydrolysis kinetics owing to the differences in conformation, since Rab11a and Rab11b do not show an α-helical switch 2 region like other Rab GTPases. Rab11b shares 90% amino acid identity to Rab11a. Kinetic experiments with Rab11a/b and Rab11-interacting proteins (FIPs) indicate that FIPs cannot differentiate between GTP-bound Rab11a and Rab11b in vitro. The major divergence reveals in the inactive state. While Pasqualato et al. crystallized inactive Rab11a as a dimer in the asymmetric unit, Scapin et al. observed single crystallographically independent monomers of both the GDP- and the GppNHp-bound Rab11b structures.

Clinical significance Due to their crucial importance in vesicle transport and recycling, Rab11 proteins are linked to various non-pathogen or pathogen induced diseases. Most of the published data do not specify whether it is the a- or the b-isoform. Rab11 proteins have been implicated in Alzheimer's disease, Arthrogryposis-renal dysfunction-cholestasis (ARC), Batten disease, and Charcot-Marie-Tooth Neuropathy Type 4C (CMT4C). Intracellular bacteria Chlamydia pneumoniae and Chlamydia trachomatis that replicate in membrane bound compartments hijack the trafficking machinery recruiting Rab GTPases to promote their replication within the host cell. Knock down of Rab11 decreased the formation of infectious particles. Recent studies report a similar use of intracellular trafficking by Hantavirus and Influenza A virus. Replicated viruses benefit from Rab11 mediated recycling endosome pathway to exit the cell and infect surrounding tissue.

References

Illustrations

Worked examples

Example 1 — a first encounter with RAB11B

Start with the simplest possible case. Write down what RAB11B claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to RAB11B before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about RAB11B ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of RAB11B

In research: RAB11B appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses RAB11B in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: RAB11B is common in secondary-school and first-year university syllabi. It links to neighbouring topics G proteins, Genes on human chromosome 19, Human proteins, so understanding it makes those chapters shorter.
In everyday life: Look for RAB11B outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “RAB11B” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study RAB11B in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what RAB11B means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain RAB11B out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is RAB11B in simple terms?

Ras-related protein Rab-11B is a protein that in humans is encoded by the RAB11B gene. Rab11b is reported as most abundantly expressed in brain, heart and testes.

Why does RAB11B matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study RAB11B?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on RAB11B.